1. Field of the Invention
The present invention relates to an automatic swiveling turret apparatus used in a machine tool such as a large vertical lathe or the like.
2. Description of the Related Art
Automatic swiveling turret apparatuses, in which a plurality of tools that can be switched for use by swiveling are installed on a turret, and this turret is automatically swiveled with respect to a turret stand when the tools are switched, generally have the following construction (parts that are the same as in the present embodiment will be described using the same symbols while referring to the drawings showing the present embodiment).
There is provided a clutch device 4, in which a turret 3 on which a plurality of tools (a plurality of cutting tools 14 respectively disposed in a replaceable manner in a plurality of holders 20) are disposed, is swivelably fit over a swiveling shaft part 2 that is fastened in a protruding manner to the turret stand 1. The turret 3 is provided in a reciprocatingly slidable manner along the swiveling shaft part 2. An indexed position of the turret is anchored and fastened in a manner that allows free disengagement by the sliding of this turret 3 in the axial direction, and the system is devised so that the anchoring and fastening of the clutch device 4 are released (unclamped) by sliding the turret 3 toward the distal end part from the base end part, thus allowing free swiveling of the turret 3, and so that the turret 3 is again caused to perform a return sliding movement at the indexed position following swiveling, and is anchored and fastened (clamped) by the clutch device 4 so that swiveling is impossible.
In concrete terms, a swiveling gear part 17 which engages with a transmission gear 16 that is driven by a calculated swiveling driving device 15 is disposed on this turret 3, and a clutch anchoring part 18 is disposed on the turret stand 1 as a clutch device 4; furthermore, a clutch engaging part 19 which makes a rotation-stopping interlocking engagement with the clutch anchoring part 18 is disposed on the base end part of the turret 3, and the system is constructed so that when the turret 3 is caused to slide toward the distal end part from the base end part, the engagement between the clutch anchoring part 18 and clutch engaging part 19 is released so that swiveling becomes possible, and the turret 3 is caused to perform indexed swiveling by the indexed swiveling driving device 15 as a result of the engagement of the swiveling gear part 17 and transmission gear 16.
There is further provided a hydraulic sliding driving mechanism, which comprises an oil supply device used for sliding driving, a clutch release pressure chamber 6 which causes the turret 3 to slide in the axial direction by allowing oil to flow in from this oil supply device via a solenoid valve, thus releasing the anchoring and fastening of the clutch device 4, and a clutch pressure chamber 7A which constitutes a sliding movement gap 7 that is reduced by sliding in order to release the clutch of this turret 3, and which causes return sliding of the turret 3 by conversely switching the solenoid valve and causing oil to flow thereinto, thus again anchoring and fastening the clutch device 4.
To describe this further, a protruding part 21 is disposed on the swiveling shaft part 2, and the turret 3 is constructed so that gap parts which are blocked off by being sealed from each other by O-rings or the like and which are widened or narrowed by the sliding of the turret 3 are formed on both the base end and distal end of this protruding part 21. One gap part which is formed by this turret 3 and the distal end side surface of the protruding part 21 is used as the clutch release pressure chamber 6, and the other gap formed by this turret 3 and the base end side surface of the protruding part 21 is used as the clutch pressure chamber 7A constituting the sliding movement gap 7. The system is constructed as shall be described next. Namely, as a result of oil being caused to flow into the clutch release pressure chamber 6 by the oil supply device via an air supply passage 22 formed in the swiveling shaft part 2 or protruding part 21, this clutch release pressure chamber 6 is pushed open, the turret 3 is caused to slide toward the distal end part with respect to the protruding part 21 which is the fastening side, and the engagement/fastening of the clutch device 4 is released. As a result of oil conversely being caused to flow into the clutch pressure chamber 7A, the clutch pressure chamber 7A is pushed open, the turret 3 is caused to undergo return sliding toward the base end with respect to the protruding part 21 which is the fastening side, and the indexed position of the turret 3 is anchored and fastened by the clutch device 4.
In such a machine tool, not only the weight of the turret itself equipped with a plurality of tools in a manner that allows switching by swiveling, but also a large load, is applied during working, especially turning. Accordingly, a large clamping force is required. Accordingly, as was described above, in the sliding driving of the turret in a conventional automatic swiveling turret apparatus as well, it is necessary to use a hydraulic sliding mechanism, and to maintain by pushing the anchored and fastened state of the clutch by the hydraulic pressure generated by this large clamping force following the completion of the turret swiveling.
Furthermore, on the one hand, the clutch device is anchored and fastened by thus causing the return sliding of the turret using the hydraulic pressure generated by the large clamping force (return sliding driving force of the turret). Since a construction is used in which this clutch device is released by causing sliding of the turret using the hydraulic pressure generated by this large clamping force, the clutch release pressure chamber that allows oil to flow in is designed as small as possible in order to prevent a greater-than-necessary sliding driving force from being generated when the turret is caused to slide for the purpose of swiveling (i.e., in order to release the clutch). Furthermore, even if this is designed as a fairly small chamber, the sliding driving force generated by the hydraulic pressure is still fairly large; accordingly, when the sliding movement gap 7 is reduced and caused to disappear by this sliding for the purpose of clutch release so that a state of abutment is achieved, a large sliding frictional resistance is generated during clamping and swiveling by this abutting surface because of pressing caused by this hydraulic force.
Specifically, since the turret is caused to undergo return sliding by the hydraulic pressure and the anchored and fastened state caused by the clutch device is pressed and maintained, even the large load during working can be resisted; on the other hand, when the turret is swiveled after this turret is caused to slide in order to release the clutch, the sliding pressing force caused by the hydraulic pressure is large. Accordingly, a large sliding frictional resistance is generated during swiveling, resulting in severe wear and compromised durability. There is therefore a danger that biting will occur during swiveling.
Conventionally, therefore, in order to solve such problems, it has been necessary to install a hydraulic pressure reducing mechanism or the like as indicated for example in Japanese Laid-open Utility Model Application No. 57-149903 in which a bypass path is caused to communicate when the flow of oil into the clamping release pressure chamber exceeds a specified pressure, or sliding occurs in excess of a specified stroke, thus causing oil to flow into the opposite sliding movement gap (clutch pressure chamber) via this bypass path from the clamping release pressure chamber that was previously blocked off, and reducing the sliding driving.
Accordingly, problems such as a complicated structure and control, an increase in cost, a deterioration in mass production characteristics, and the like were generated, and problems have also been presented in terms of a slow unclamping speed for the release of clamping (turret swiveling), and the like.
It is an object of the present invention to conserve resources in a hydraulic-free system. Focusing on the sliding driving mechanism of the turret that engages, fastens and holds the clutch-engaged state of the turret so as to prevent swiveling, and that releases this state, as one large impediment to achieving hydraulic-free operation, the present invention overthrows the conventional concept of anchoring, and is devised so that a state in which the turret can be clutched so as to prevent swiveling can be engaged, fastened and held by an pneumatic sliding driving mechanism using an air supply device. It is an object of the present invention to provide an extremely revolutionary automatic swiveling turret apparatus for a machine tool in which the weight of the turret and a large cutting force can be sufficiently withstood by a wedge mechanism even in the case of an air type sliding driving mechanism not capable of generating a driving force that can directly withstand a large cutting force (turning force), in which, as a result, hydraulic-free operation can be realized and energy and resources can be saved without hindering turret swiveling or the cutting function, and in which a smooth swiveling function with superior durability can easily be ensured and the unclamping speed during swiveling can also be increased merely by installing a simple resistance-reducing member of a dry bearing or the like on the abutting surface (sliding surface during swiveling) of the turret during release of the engagement, without any need to install a hydraulic pressure reducing mechanism requiring complicated design and control of the type described above due to this conversion to hydraulic-free operation.